1. Field of the Invention
The present invention relates to an image pickup lens, an image pickup apparatus, and a control method of the image pickup apparatus.
2. Description of the Related Art
Japanese Patent Laid-Open No. (“JP”) 2004-233892 discloses an image pickup apparatus configured to drive a magnification variable lens using a variable magnification ring and a zoom key, and to maintain a correlation between a position of the variable magnification ring and a position of the magnification variable lens. JP 07-281072 discloses an image pickup apparatus that includes a wide attachment (“WA”) lens attachable to an optical system that includes a magnification variable lens and configured to change a focal length and an enlargement ratio of the optical system (for example, so as to obtain an image having a wider angle of view).
However, for an image pickup apparatus that is made by combining these two references with each other, a cam curve that represents a position used for a focus lens to maintain an in-focus state relative to a position of the magnification variable lens when the WA lens is attached is different from that when the WA lens is not attached. The in-focusing range of the focus lens when the WA lens is attached is narrower than the in-focusing range of the focus lens when the WA lens is not attached.
More specifically, if it is assumed that the magnification variable ring has a rotatable range from 0° to θ°, the magnification variable lens has a maximum moving distance of L, and an in-focusable maximum moving distance of the magnification variable lens when the WA lens is attached is Lw (L>LW), an in-focusable angular range of the magnification variable ring becomes between 0° and (θ×Lw/L)°. Therefore, in a range between (θ×Lw/L)° and θ° on the telephoto side, although the magnification variable ring is manipulated, a good image pickup state cannot be provided because the magnification variable lens cannot be driven or the in-focus cannot be maintained.